JP7560493B2 - Absorbent articles - Google Patents

Description

The present invention relates to an absorbent article.

There is a known technology for deforming the absorbent body in order to improve the fit and leakage prevention in the crotch area when absorbent articles such as disposable diapers and sanitary napkins are worn. For example, Patent Document 1 describes a disposable diaper in which the absorbent body is composed of a central absorbent body and a pair of side absorbent bodies, with elastic members for raising the side absorbent bodies on both sides of the absorbent body. With this diaper, the side absorbent bodies rise due to the contraction force of the elastic members when worn, so that the width of the crotch area is narrowed, improving the fit, and the raised side absorbent bodies make it less likely for side leakage to occur.

Technologies have also been proposed to improve the fit of diapers by making the absorbent body thinner. For example, Patent Document 2 describes a disposable diaper with a two-layer absorbent body, an upper absorbent body and a lower absorbent body, in which the upper absorbent body is made of pulp and absorbent polymer, and the lower absorbent body is made of two sheets with absorbent polymer placed between them.

JP 2006-341061 A JP 2018-50987 A

The absorbent article of the present invention comprises a top sheet, a back sheet, and an absorbent body disposed between these sheets.
The top sheet covers the skin-facing surface of the absorbent body and has a pair of extending portions extending laterally from each side edge of the absorbent body, and each of the extending portions is folded back at each side edge of the absorbent body to cover each side of the non-skin-facing surface of the absorbent body.
Each of the extensions is joined to a non-skin side member adjacent to the absorbent body on the non-skin facing surface.
The absorbent body includes an absorbent sheet having two identical or different fibrous sheets and particles of absorbent polymer disposed between the fibrous sheets.
Elastic members are disposed along each side edge of the absorbent body between the absorbent body and the topsheet.
Contraction of the elastic members allows each side of the absorbent body to stand up, starting from the joining position between the absorbent body and the non-skin side member.
The absorbent sheet is present at least in a portion of the absorbent body that can stand up due to contraction of the elastic members.

FIG. 1 is a schematic perspective view of a pants-type diaper according to a first embodiment of the present invention. FIG. 2 is a schematic plan view, partly cut away, of the diaper shown in FIG. 1 after it has been cut apart at the side seals and laid out flat with the elastic members of each section stretched. FIG. 3 is a schematic cross-sectional view in the width direction illustrating a schematic configuration of the absorbent body in the diaper shown in FIG. FIG. 4 is a cross-sectional view showing a schematic cross section taken along line IV-IV in FIG. FIG. 5 is a cross-sectional view showing a schematic cross section taken along line VV in FIG. FIG. 6(a) is an enlarged view showing the absorbent body before it absorbs liquid, and FIG. 6(b) is an enlarged view showing the absorbent body after it absorbs liquid. FIG. 7 is a perspective view showing a typical wearing state of the embodiment of the present invention when seated. FIG. 8 is a schematic diagram illustrating a schematic configuration of a modified example of the absorbent body.

Detailed Description of the Invention

As described above, various technologies are known for improving the fit of a diaper when worn, but no diaper has been proposed to date that maintains its fit even after absorbing liquid and is less likely to cause discomfort when worn.
Therefore, the present invention relates to an absorbent article in which the absorbent body remains soft even after absorbing liquid and which is less likely to cause discomfort when worn.

The absorbent article of the present invention will be described below based on a preferred embodiment with reference to the drawings. This embodiment relates to a disposable diaper (hereinafter, also referred to as "diaper") as an example of an absorbent article. As shown in Figs. 1 to 5, the diaper 1 is a so-called pants-type diaper, and includes an absorbent body 5 having a top sheet 2, a back sheet 3, and a liquid-retaining absorbent body 4 arranged between these sheets. The top sheet 2 is liquid-permeable. The back sheet 3 is liquid-impermeable or poorly liquid-permeable. Furthermore, the diaper 1 includes an exterior body 10 on the non-skin-contacting surface side of the absorbent body 5.
As shown in Figures 1 and 2, the absorbent body 5 has a generally vertically elongated rectangular shape in a plan view along the longitudinal direction X of the diaper 1, and is entirely covered with a water-permeable covering sheet (not shown) made of tissue paper or a water-permeable nonwoven fabric.
As shown in FIG. 2, the diaper 1 is divided into a ventral portion A which is disposed on the ventral side of a wearer when worn, a dorsal portion B which is disposed on the dorsal side of the wearer, and a crotch portion C which is located therebetween.

In this specification, the "non-skin contacting side" refers to the side (surface) of either the front or back side (surface) of each component, such as the absorbent body, that is disposed opposite the wearer's skin when worn. In the following, the phrase "skin contacting side" may be used, which refers to the side (surface) of either the front or back side (surface) of each component that is disposed opposite the wearer's skin when worn. The "longitudinal direction X" refers to the direction parallel to the long side of each component. In the following, the phrase "width direction Y" may be used, which refers to the direction perpendicular to the longitudinal direction X.

As shown in Figure 2, the absorbent body 5 has a vertically elongated rectangular shape, and is joined to the widthwise center of the exterior body 10 by a known joining method such as a hot melt adhesive so as to extend from the abdominal portion A to the dorsal portion B, with its longitudinal direction X coinciding with the longitudinal direction X of the diaper. The exterior body 10 has both sides of the portion located in the abdominal portion A and both sides of the portion located in the dorsal portion B joined to each other by a known joining method such as heat sealing, high frequency sealing, ultrasonic sealing, etc., to form a pair of side seal portions as shown in Figure 1. This joining also forms a waist opening 7 and a pair of leg openings 8, 8 in the diaper 1.

The exterior body 10 forms the contour of the diaper. In a plan view, both side edges of the central region of the exterior body in the longitudinal direction X are curved toward the center in the width direction Y. This region is the crotch portion C. Regions extending from the crotch portion C to the front and rear in the longitudinal direction X are the ventral portion A and the dorsal portion B.
As shown in Figures 2, 4 and 5, the outer body 10 is composed of two sheets for forming an outer body and elastic members at each part fixed between the two sheets. Figure 5 is a diagram showing the natural state in which the elastic members are contracted. Between the outer layer sheet 11 and the inner layer sheet 12 constituting the two sheets for forming an outer body, a waist elastic member 71 for forming waist gathers on the periphery of the waist opening 7, a leg elastic member 81 for forming leg gathers on the periphery of the leg opening 8, and a waist elastic member 91 for forming waist gathers divided into left and right in the waist portion D (the region from a position spaced downward from the periphery of the waist opening 7 to the upper end of the leg opening 8) are bonded and fixed in a stretched state by a bonding method such as a hot melt adhesive.

The outer layer sheet 11 and the inner layer sheet 12 are preferably both made of breathable nonwoven fabric. Of these two sheets, the outer layer sheet 11 located on the non-skin contact side has extensions extending in the longitudinal direction X from the front and rear end edges of the inner layer sheet 12 located on the skin contact side. After the absorbent body 5 is placed on the inner layer sheet 12, these extensions are folded back and adhered to the absorbent body 5 side so as to cover the front and rear end portions (both ends in the longitudinal direction X) of the absorbent body 5.

As shown in Fig. 4, the topsheet 2 covers the skin-facing surface of the absorbent body 4. In addition, the topsheet 2 has a pair of extending portions 2a, 2b that extend outward in the width direction Y from each side edge 4c, 4d of the absorbent body 4. The extending portions 2a, 2b of the topsheet 2 are folded back at each side edge 4c, 4d of the absorbent body 4 to cover each side portion 4e, 4f of the non-skin-facing surface of the absorbent body 4. The extending portions 2a, 2b of the topsheet 2 are each joined to the backsheet 3, which serves as a non-skin-side member, adjacent to the absorbent body 4 on the non-skin-facing surface.
The topsheet 2 is joined and fixed at its both side edge portions 21, 21 to the backsheet 3 and the leakage-preventive cuff-forming sheet 60 to form main body joining and fixing portions 67, 67 which serve as joining positions. The main body joining and fixing portions 67 are formed by joining the leakage-preventive cuff-forming sheet 60, the side edge portions 21 of the topsheet 2, and the backsheet 3 using a known joining means such as heat sealing, high-frequency sealing, ultrasonic sealing, or a hot-melt adhesive.

A leak-proof cuff-forming sheet 60 and an absorbent body 5 are joined in this order to the skin-contacting surface of the exterior body 10. The exterior body 10 and the leak-proof cuff-forming sheet 60 are joined by an exterior body joining and fixing part 13. The exterior body joining and fixing part 13 is disposed at a position outside the main body joining and fixing part 67 in the diaper width direction. A joining method such as a hot melt adhesive can be used to join each of these components.

A pair of leak-proof cuffs 6, 6 are formed on both sides of the width direction Y of the absorbent body 5. The leak-proof cuff 6 is formed to extend in the longitudinal direction X of the diaper and includes a leak-proof cuff forming sheet 60, multiple leak-proof cuff forming elastic members 61, and one leak-proof cuff pulling elastic member 62. The leak-proof cuff forming sheet 60 is joined to the absorbent body 5. The leak-proof cuff forming elastic member 61 is fixed in a stretched state near the free end of the leak-proof cuff forming sheet 60. The leak-proof cuff pulling elastic member 62 is fixed in a stretched state between the main body joining and fixing part 67 constituting the fixed end of the leak-proof cuff 6 and the free end. The leak-proof cuff pulling elastic member 62 is continuously arranged over the entire longitudinal direction of the leak-proof cuff forming sheet 60 (leak-proof cuff 6) between the leak-proof cuff forming elastic member 61 and the main body joining and fixing part 67 in the leak-proof cuff 6.

In this embodiment, the leak-proof cuff-forming sheet 60 is a two-layered sheet made by folding a strip-shaped water-repellent sheet of a specified width in half along a folding axis along the longitudinal direction X and bonding the opposing layers with a hot melt adhesive or partial heat sealing or ultrasonic sealing, etc. The leak-proof cuff-forming elastic member 61 and one leak-proof cuff-pulling elastic member 62 are fixed in a stretched state between the layers of this two-layered sheet.

As shown in FIG. 2, the leak-proof cuff-forming sheet 60 is in contact with the skin-contacting surface of the absorbent body 5 in each of the ventral portion A and the dorsal portion B, more specifically, in each of both ends in the longitudinal direction X of the absorbent body 5, while covering the skin-contacting surface of the absorbent body 5. The leak-proof cuff-forming sheet 60 is not joined to the absorbent body 5 in a portion other than the joint with the absorbent body 5. As a result, the leak-proof cuff 6 can stand up at least in the crotch portion C, as shown in FIG. 5. As described above, in the vicinity of the free end of the leak-proof cuff 6 (the folded end of the leak-proof cuff-forming sheet 60), multiple elastic members 61 for forming the leak-proof cuff are fixed over the entire longitudinal direction of the leak-proof cuff-forming sheet 60 (leak-proof cuff 6) in a state of being arranged in the width direction Y of the absorbent body 5. With this configuration, the tip portion of the standing leak-proof cuff 6 comes into surface contact with the wearer's skin. As a result, the diaper 1 fits closely to the body, improving the leak-proofing performance, and the leak-proof cuffs 6 can be made to come into gentle contact with the skin.

In the diaper 1, elastic members 9 are arranged between the absorbent body 4 and the top sheet 2 along each side edge 4c, 4d of the absorbent body 4. The elastic members 9 are arranged to be stretchable in one direction by being fixed in a stretched state. The elastic members 9 are elastic members for raising the absorbent body, and are arranged in a position inward in the diaper width direction from the elastic members 62 on the leak-proof cuff 6 side when the diaper 1 is in an unfolded state. As a result, the absorbent body 4 is configured so that both side portions 4e, 4f in the width direction Y of the crotch portion C are raised. That is, as shown in FIG. 5, the absorbent body 4 is configured so that each side portion 4e, 4f of the absorbent body 4 can be raised from the main body joining and fixing portions 67, 67, which are the joining positions between the absorbent body 4 and the back sheet 3, as a starting point due to the contraction of the pair of elastic members 9.

The absorbent body 4 has an absorbent sheet 42 and an auxiliary layer 41 having a structure different from that of the absorbent sheet 42. As shown in Figs. 6(a) and (b) described later, the absorbent sheet 42 has two sheets, a first fiber sheet 421 and a second fiber sheet 422, on the outermost surface. The auxiliary layer 41 is laminated on the upper surface of the absorbent sheet 42 and arranged in the center of the absorbent sheet 42 in the width direction Y. In the diaper 1, the absorbent sheet 42 is at least present in the absorbent body 4 at a portion that can stand up due to the contraction of each elastic member 9. In this embodiment, the portion that can stand up of the absorbent body 4 is a portion in the region from the main body joining and fixing portions 67, 67 to the portions 2c, 2d located outside the width direction Y of the top sheet 2 when the absorbent body 4 protrudes most outward in the width direction Y of the absorbent body 4, as shown in Fig. 3. When the absorbent sheet 42 is used as a reference, it is a portion located in a straight-line distance section L from the joint with the main body joining and fixing parts 67, 67 to portions 2c, 2d of the topsheet 2 existing outside both side edges 42a, 42b of the absorbent sheet 42 that are located outside the main body joining and fixing parts 67, 67. In this embodiment, each side portion 4e, 4f of the absorbent body 4 is a portion located in this straight-line distance section L.

Conventional disposable diapers tend to be loose around the crotch area C when worn, making it difficult to move the legs and uncomfortable to wear. Although there are conventional technologies for reducing the thickness of the absorbent body 4 itself, none of them have focused on improving the standing ability of each side portion 4e, 4f of the absorbent body 4 in addition to reducing the thickness of the absorbent body 4. Furthermore, although there are technologies for making each side portion 4e, 4f of the absorbent body 4 stand up, there are no technologies that focus on improving the uncomfortable feeling of wearing the diaper after absorption by using a technology for thinning the absorbent body 4.

In contrast, in the diaper 1 of this embodiment, the absorbent sheet 42 is present in the side portions 4e, 4f of the absorbent body 4 that can stand up from the main body joint fixing portions 67, 67 due to contraction of the elastic members 9, 9, so that the thickness change of both side portions 4e, 4f in the width direction Y of the absorbent body 4 after absorbing liquid can be suppressed. As a result, the surface 4a of the absorbent body 4 that contacts the skin and the surface 4b of the absorbent body 4 that does not contact the skin remain flexible even after absorbing liquid, and a diaper 1 that does not cause discomfort when worn can be provided.

7, the leak-proof cuff 6 is provided with an elastic member 62 for pulling the leak-proof cuff, and the contraction force of the elastic member 62 pulls the area of the leak-proof cuff 6 between the free end where the elastic member 61 for forming the leak-proof cuff is located and the exterior body joining and fixing part 13 constituting the fixed end toward the wearer's legs. Due to this, the side parts 4e, 4f of the absorbent sheet 42 constituting both sides in the width direction Y of the absorbent body 4 are pulled toward the wearer's legs via the top sheet 2 joined to the leak-proof cuff forming sheet 60, and are easily fitted to the legs. Furthermore, by the side parts 4e, 4f of the absorbent sheet 42 standing up and being pulled toward the legs, the auxiliary layer 41 located in the center of the width direction is also pulled outward in the width direction, and the shape of the auxiliary layer 41 is stabilized (improved shape retention). As a result, the feeling of neatness of the crotch part C is improved, and the leak-proof performance is also improved.

In addition, since the outer body joint fixing part 13 is located at a position outside the main body joint fixing part 67 in the diaper width direction, when the outer body 10 is pulled outward in the width direction by the contractile force of the leg elastic members 81 arranged at the leg openings 8, the absorbent body 4 (absorbent sheet 42, auxiliary layer 41) is also efficiently pulled outward in the width direction via the outer body joint fixing part 13, the leakproof cuff forming sheet 60, and the main body joint fixing part 67. As a result, the neatness and leakproof performance of the crotch part C are further improved.

In this embodiment, the auxiliary layer 41, which has a structure different from the absorbent sheet 42 of the absorbent body 4, is arranged between the parts Ya (see FIG. 3) that can stand up, so that the standing of the side parts 4e, 4f is not hindered by the auxiliary layer 41, and discomfort is less likely to occur when worn. Furthermore, since the auxiliary layer 41 absorbs liquid, the absorbent sheet 42 absorbs less liquid, and the thickness change of the absorbent sheet 42 after absorption is suppressed, so that it is preferable because it has good shape retention and is less likely to cause discomfort when worn while ensuring absorbency. Furthermore, it is preferable because the surface 4a on the skin contact side and the surface 4b on the non-skin contact side of the absorbent body 4 are soft even after absorbing liquid, and the feeling of rubbing when worn can be reduced.

It is preferable that the stiffness value of the absorbent body 4 in the central region of the diaper 1 is set to at least twice the stiffness value of the absorbent sheet 42 alone. This ensures the stiffness even when the side portions 4e, 4f, which are upstandable portions, stand up in the crotch portion C when the diaper 1 is worn, and provides the advantage of good shape retention. If the stiffness value in the central region of the diaper 1 is preferably at least 2.0 times, more preferably at least 3.0 times, and even more preferably at least 4.0 times the stiffness value of the absorbent sheet 42 alone, the shape retention is further improved.

From the viewpoint of improving liquid absorption, the thickness of the absorbent sheet 42 is preferably 0.3 mm or more, more preferably 0.6 mm or more. From the viewpoint of improving the user's comfort when using an absorbent article including the absorbent sheet 42, the thickness of the absorbent sheet 42 is preferably 4 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less. The above-mentioned thickness of the absorbent sheet 42 is the thickness of the entire absorbent sheet measured under the application of a pressure of 1.7 kPa.

The auxiliary layer 41 is composed of, for example, a laminate of synthetic fibers and/or absorbent natural fibers, or a laminate of synthetic fibers and/or absorbent natural fibers and absorbent polymer particles. In particular, it is preferable that the auxiliary layer 41 is composed of a mixed laminate of fluff pulp and absorbent polymer particles in order to increase the absorption capacity of the absorbent body 4. When the auxiliary layer 41 is composed of, for example, a mixed laminate of fluff pulp and absorbent polymer particles, the basis weight of the absorbent polymer is preferably 65 to 800 g/m ² , more preferably 70 to 600 g/m ² , and the basis weight of the fluff pulp is preferably 80 to 600 g/m ² , more preferably 100 to 400 g/m ² .

In this embodiment, when the FSR is defined as the mass ratio of absorbent polymer to the total amount of absorbent material other than each fiber sheet 421, 422 in the absorbent sheet 42 constituting the absorbent body 4 and the absorbent material in the auxiliary layer 41 constituting the absorbent body 4, it is preferable that the FSR of the side portions 4e, 4f, which are the parts of the absorbent body 4 that can stand up, is greater than the FSR of the part 4g between the parts that can stand up. This makes the absorbency of the center of the absorbent body 4 higher than both side portions 4e, 4f in the width direction, and makes it easier to maintain high shape retention even after absorbing liquid.

In order to make the above-mentioned advantages more prominent, the ratio of the FSR in the side portions 4e, 4f to the FSR in the portion 4g is preferably 1.1 or more, more preferably 1.3 or more. Moreover, the ratio is preferably 5.0 or less, more preferably 3.5 or less. In particular, the ratio is preferably 1.1 or more and 5.0 or less, more preferably 1.3 or more and 3.5 or less. The "liquid-absorbent material other than the fiber sheets 421, 422 in the absorbent sheet 42" refers to the fiber material and absorbent polymer other than the fiber sheets 421, 422 in the absorbent sheet 42. The "liquid-absorbent material in the auxiliary layer 41" refers to the fiber material and absorbent polymer contained in the auxiliary layer 41.

When the ratio of the absorbent polymer content of the auxiliary layer 41 to the total mass of the constituent materials of the auxiliary layer 41 is PR1, and the ratio of the absorbent polymer content of the absorbent sheet 42 to the total mass of the constituent materials of the absorbent sheet 42 is PR2, the ratio of PR2 to PR1 (PR2/PR1) is preferably 1.1 or more, and more preferably 1.3 or more. Moreover, this ratio is preferably 5.0 or less, and more preferably 3.5 or less. In particular, this ratio is preferably 1.1 or more and 5.0 or less, and more preferably 1.3 or more and 3.5 or less.

It is preferable that the absorbent body 4 has a larger change in thickness before and after liquid absorption in the auxiliary layer 41 than in the absorbent sheet 42. With this configuration, as shown in Fig. 6(b), the change in thickness of the absorbent sheet 42 after liquid absorption can be suppressed compared to the auxiliary layer 41. As a result, the surface 4a of the absorbent body 4 that contacts the skin and the surface 4b of the absorbent body 4 that does not contact the skin are soft even after liquid absorption, which is preferable since it reduces the feeling of friction when worn. In addition, it is preferable since it improves the shape retention in the center of the absorbent body 4.
From the viewpoint of making this effect more prominent, the difference between the thickness change in the auxiliary layer 41 and the thickness change in the absorbent sheet 42 is preferably 1 mm or more, and more preferably 2 mm or more. Moreover, the difference between the thickness change in the auxiliary layer 41 and the thickness change in the absorbent sheet 42 is preferably 20 mm or less, and more preferably 15 mm or less. In particular, the difference between the thickness change in the auxiliary layer 41 and the thickness change in the absorbent sheet 42 is preferably 1 mm or more and 20 mm or less, and more preferably 2 mm or more and 15 mm or less.

The amount of thickness change _T0c in the auxiliary layer 41 or the absorbent sheet 42 can be calculated from the following formula.
T0 _c = T0 _w - T0 _d
T0 _w : Thickness of the auxiliary layer 41 or absorbent sheet 42 under a load of 4.9 mN/cm ² after absorbing liquid T0 _d : Thickness of the auxiliary layer 41 or absorbent sheet 42 under a load of 4.9 mN/cm ² before absorbing liquid

The thickness change amount _T0c of the absorbent sheet 42 is preferably 0.5 mm or more, more preferably 1 mm or more, and is preferably 25 mm or less, more preferably 15 mm or less. The thickness change amount _T0c is preferably 0.5 mm or more and 25 mm or less, more preferably 1 mm or more and 15 mm or less.
The thickness _T0d of the absorbent sheet 42 before liquid absorption is preferably 0.1 mm or more, more preferably 0.3 mm or more, and is preferably 5 mm or less, more preferably 3 mm or less. The thickness _T0d before liquid absorption is also preferably 0.1 mm or more and 5 mm or less, more preferably 0.3 mm or more and 3 mm or less.
The thickness _T0w of the absorbent sheet 42 after absorbing liquid is preferably 1 mm or more, more preferably 2 mm or more, and is preferably 30 mm or less, more preferably 15 mm or less. Also, the thickness _T0w after absorbing liquid is preferably 1 mm or more and 30 mm or less, more preferably 2 mm or more and 15 mm or less.

The thickness change _T0c of the auxiliary layer 41 is preferably 2 mm or more, more preferably 4 mm or more, and is preferably 45 mm or less, more preferably 35 mm or less, and is also preferably 2 mm or more and 45 mm or less, more preferably 4 mm or more and 35 mm or less.
The thickness _T0d of the auxiliary layer 41 before absorbing liquid is preferably 1 mm or more, more preferably 3 mm or more, and is preferably 15 mm or less, more preferably 12 mm or less, and is also preferably 1 mm or more and 15 mm or less, more preferably 3 mm or more and 12 mm or less.
The thickness _T0w of the auxiliary layer 41 after absorbing liquid is preferably 5 mm or more, more preferably 10 mm or more, and preferably 50 mm or less, more preferably 30 mm or less, and also preferably 5 mm or more and 50 mm or less, more preferably 10 mm or more and 30 mm or less.

Next, a method for measuring the thickness change _T0c before and after liquid absorption will be described.
The measurement device used is a KES-G5 handy compression tester manufactured by Kato Tech Co., Ltd. The sample is attached to the test stand of the measurement device, and compressed between plywood boards with a circular flat surface of ² cm2, applying a load of 4.9 mN/ ^cm2 (=0.5 gf/ ^cm2 ) to the sample, and the thickness of the sample is measured in this state. The compression speed is 0.5 mm/sec, and the maximum compression load is 490 mN/ ^cm2 (=50 gf/ ^cm2 ).
When measuring the thickness T0 _d (mm) under a load of 4.9 mN/cm ² before absorbing liquid, the sample in a dry state is used as it is as the measurement sample.
When measuring the thickness _T0w (mm) under a load of 4.9 mN/ ^cm2 after absorbing liquid, a dry sample is immersed in physiological saline for 30 minutes, and then the moisture is wiped off using an absorbent sheet such as Kimtowel to the extent that no moisture leaks from the sample (sample after absorbing liquid) and used as the measurement sample.
The thickness change before and after liquid absorption, T0 _c (mm), is calculated by subtracting the thickness before liquid absorption, T0 _d (mm), from the thickness after liquid absorption, T0 _w (mm) (T0 _w - T0 _d ).

3, the length L1 of the auxiliary layer 41 along the width direction Y is set to be longer than the length L2 between the main body joint fixing parts 67, 67. In detail, both side edges 41a, 41b of the auxiliary layer 41 protrude in the width direction Y from the main body joint fixing parts 67, 67. For this reason, the auxiliary layer 41 is formed such that the length L3 from both side edges 41a, 41b of the auxiliary layer 41 in the width direction Y to the parts 2c, 2d of the topsheet 2 is shorter than the length L of the standable part.
The widthwise side portions 4e, 4f of the absorbent body 4 that are capable of standing up are preferably positioned so that the absorbent sheet 42 occupies at least 75% of the length of the region inwardly from the widthwise side edges 4c, 4d of the absorbent body 4. In other words, the widthwise side portions 4e, 4f of the absorbent body preferably have an area where the absorbent sheet 42 is present and the auxiliary layer 41 is not present. In this way, it is possible to ensure liquid absorption without impeding the ability to stand up. From the viewpoint of making this advantage even more pronounced, the proportion of the absorbent sheet 42 that is occupied by the absorbent sheet 42 is preferably 78% or more, more preferably 82% or more, and even more preferably 85% or more.

8, the auxiliary layer 41 may have a recess 45 that serves as a low-rigidity region extending in the longitudinal direction X of the diaper 1. In this case, the recess 45 may be formed in the auxiliary layer 41 so as to be located between the portions Ya of the absorbent body 4 that can stand up. In the auxiliary layer 41, the portion where the recess 45 is formed has a smaller amount of fiber and absorbent polymer per unit area than the portion where the recess 45 is not formed, forming a low-rigidity region with low rigidity. Therefore, in the crotch portion C after wearing, the auxiliary layer 41 is easily deformed in the width direction Y, which is preferable because it is possible to reduce the feeling of stiffness while maintaining shape retention.

In the embodiment described above, the elastic members 9, 9 are disposed between the topsheet 2 and the absorbent sheet 42, but arrangements other than this embodiment are also possible.

Next, the configuration of the absorbent sheet 42 will be described.
The absorbent sheet 42 is formed by bonding two identical fibrous sheets 421 and 422 with an adhesive 425. In the embodiment shown in Figures 6(a) and (b), the adhesive 425 is disposed on the fibrous sheet 421 and the surface of the fibrous sheet 422 facing the absorbent polymer 423. Figure 6(a) shows a schematic diagram of the state of the absorbent body 4 before absorbing liquid, and Figure 6(b) shows a schematic diagram of the state of the absorbent body 4 after absorbing liquid. In these figures, the arrow Z indicates the thickness direction of the absorbent body 4.

When the absorbent sheet 42 is viewed in a plan view, the absorbent polymer 423 is arranged in a manner that no macroscopically visible gaps are observed in the area where the absorbent polymer 423 is arranged. "No macroscopically visible gaps are observed" means that when the area where the absorbent polymer 423 is dispersed is viewed with the naked eye, the absorbent polymer 423 is arranged to cover one side of the fiber sheet evenly, but when the area is viewed microscopically, it is acceptable that gaps between the absorbent polymers 423 are formed unintentionally. These gaps are approximately 10 to 1000 μm. In the following description, the gaps between the absorbent polymers 423 observed microscopically in the area where the absorbent polymer 423 is dispersed are also referred to as "microscopic gaps."

In the region where the absorbent polymer 423 is dispersed, the fiber sheet 421 and the fiber sheet 422 have a portion 427 (hereinafter, also referred to as the "directly bonded portion 427") that is directly bonded by the adhesive 425 without the absorbent polymer 423. The direct bonded portion 427 is formed in each of the microscopic voids described above. When the direct bonded portion 427 is viewed in cross section in the thickness direction Z of the sheet, the adhesive 425 forms a columnar shape and directly bonds the two fiber sheets 421 and 422 to each other. When the absorbent sheet 42 is viewed in the sheet plane direction, the direct bonded portion 427 is formed in a plurality of regular or irregular scattered dots. By forming the direct bonded portion 427, the absorbent polymer 423 can be held in a predetermined position of the absorbent sheet 42 while the liquid absorbency of the absorbent polymer 423 can be fully exhibited. Direct bonding portion 427 can be formed, for example, as described below, by appropriately adjusting the basis weight and particle size of absorbent polymer 423 or the amount and area of adhesive 425 applied.

In addition to the direct bonding portion 427, the absorbent sheet 42 preferably has a portion 428 (hereinafter also referred to as the "indirect bonding portion 428") where both fiber sheets 421, 422 are bonded by adhesive 425 via absorbent polymer 423. In the indirect bonding portion 428, when the absorbent sheet 42 is viewed in cross section, the application portion of adhesive 425 in the fiber sheet 421, the presence portion of absorbent polymer 423, and the application portion of adhesive 425 in the fiber sheet 422 overlap in the sheet thickness direction Z. With this configuration, the absorbent polymer 423 can be held at a predetermined position in the absorbent sheet 42, and unintended movement or uneven distribution of the absorbent polymer 423 can be further reduced, and the liquid absorbency of the absorbent sheet 42 can be further improved.

As the adhesive 425, it is preferable to use one that has flexibility that can expand in response to the swelling change caused by the liquid absorption of the absorbent polymer 423. Examples of such raw materials include acrylic adhesives containing one or more vinyl monomer (co)polymers (such as ethylene-vinyl acetate copolymers) including 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, cyanoacrylate, vinyl acetate, methyl methacrylate, etc., silicone adhesives containing polydimethylsiloxane polymers, etc., as well as natural rubber adhesives containing natural rubber, isoprene adhesives containing one or more polyisoprene, chloroprene, etc., rubber adhesives such as styrene-butadiene copolymers (SBR), styrene-isoprene-styrene block copolymers (SIS), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylene-butadiene-styrene block copolymers (SEBS), and styrene-ethylene-propylene-styrene block copolymers (SEPS). These may be used alone or in combination of two or more. As shown in Figures 6 (a) and (b), when adhesive 425 is disposed on the surface of each fibrous sheet 421, 422 facing the absorbent polymer 423, the adhesive disposed on fibrous sheet 421 and the adhesive disposed on fibrous sheet 422 may be of the same type or of different types.

Of these, it is preferable to use a rubber-based adhesive as the adhesive 425, from the viewpoints of excellent flexibility and elasticity, maintaining the direct bond between the fiber sheets 421, 422 even after swelling of the absorbent polymer 423, and exerting a contractile force to easily hold the absorbent polymer 423 between the fiber sheets 421, 422, and among the rubber-based adhesives, it is more preferable to use a styrene-based adhesive.

From the viewpoint of achieving both the flexibility of the adhesive and its adhesion to the sheet, it is preferable that the adhesive 425 is a hot melt adhesive. For example, the hot melt adhesive may contain, in addition to the various adhesives described above, a tackifier such as a petroleum resin or a polyterpene resin, a plasticizer such as a paraffin-based oil, and, as necessary, an antioxidant such as a phenol-based, amine-based, phosphorus-based, or benzimidazole-based.

The fiber sheet used in the present invention is an assembly of fibers, and has a thickness of 5 mm or less when measured under a pressure of 1.7 kPa. The thickness of the fiber sheet can be measured, for example, using a laser displacement meter. The constituent fibers of each fiber sheet 421, 422 include various fibers such as natural pulp such as wood pulp, cotton, and hemp, modified pulp such as mercerized pulp and chemically crosslinked pulp, and synthetic fibers containing resins such as polyethylene and polypropylene. The form of each fiber sheet 421, 422 is paper, woven fabric, or nonwoven fabric.

The adhesive 425 has a relaxation time obtained by viscoelasticity measurement of preferably 1 second or more, more preferably 2 seconds or more, and even more preferably 3 seconds or more at 50° C. When the adhesive 425 has such a value, it exhibits appropriate flexibility and stretchability, and can hold the absorbent polymer in a state where the fiber sheets 421 and 422 are directly bonded to each other even after the absorbent polymer swells.
Generally, the relaxation time is a physical property that indicates the degree of fluidity of a material, and if the relaxation time is short, the adhesive will flow easily, and the stretched portion will become thinner due to the surface tension acting when the adhesive is stretched, and this portion will be more likely to break. As a result, there is a risk that the bonded state between the fiber sheets 421, 422 will not be maintained. As a result of extensive research by the present inventors on this point, it was found that there is a high correlation between the relaxation time at 50°C and the extensibility of the adhesive, and that the longer the relaxation time at 50°C, the less likely the stretched portion caused by the stretching of the adhesive will break, making this an adhesive that is suitable for use in the present invention.

The relaxation time of the adhesive 425 at 50°C obtained by the viscoelasticity measurement is calculated as the reciprocal of the value of tan θ obtained when the dynamic viscoelasticity of the adhesive 425 is measured under the following conditions. In detail, a rotational rheometer (manufactured by Anton Paar, model number "Physica MCR301") is used, and the adhesive 425 to be measured is interposed between a receiving plate having a circular shape in a plan view that supports the measurement sample from below and a pressing plate having a circular shape in a plan view that is arranged above the receiving plate and facing the receiving plate. In this state, the adhesive 425 has a circular shape in a plan view, a thickness of 1.5 mm, and a diameter of 12 mm. The frequency during measurement is set to 1 Hz, the strain amplitude to 0.05%, and the cooling rate to 2°C/min, and the measurement is performed in the temperature range from 120°C to -10°C. tan θ is the value obtained by dividing the loss modulus G" by the storage modulus G'.

In the above-mentioned viscoelasticity measurement, if the adhesive 425 to be measured is a component of the absorbent sheet 42, the adhesive is sampled from the absorbent sheet 42 by the solvent extraction method described below, and the sampled adhesive is used as the measurement object. In addition, if the adhesive 425 to be measured is not a component of the absorbent sheet 42 and is unused, the unused adhesive is used as it is as the measurement object. The relaxation time of the adhesive may be within the above-mentioned range in at least one case, regardless of whether it is a component of the absorbent sheet 42 or not.

The solvent extraction method of the adhesive can be performed, for example, by the following method. First, in a container such as a beaker, the absorbent sheet 42 containing the adhesive 425 is mixed with a solvent capable of dissolving the adhesive 425, and the adhesive 425 is dissolved in the solvent. Next, the adhesive solution is collected by separating solids such as a fiber sheet from the adhesive solution, and the adhesive solution is dried under reduced pressure using a rotary evaporator or the like to obtain a solid adhesive. The adhesive thus obtained is used as the measurement target in the measurement of the relaxation time. The solvent used to dissolve the adhesive may be appropriately selected depending on the type of adhesive, etc. When the adhesive to be measured is a hot melt adhesive, one or more organic solvents such as toluene, methyl ethyl ketone, and heptane can be used as the solvent used to dissolve the adhesive.

According to the absorbent sheet 42 having the above-mentioned configuration, the adhesive 425 present at the direct bonding portion creates an appropriate bonding strength between the fiber sheets 421, 422 that does not cause the absorbent polymer 423 to move or fall off, and the absorbent polymer 423 can be supported at an appropriate position between the fiber sheets. In addition, since an appropriate bonding strength is created that allows the absorbent polymer 423 to swell sufficiently, the liquid absorbency of the absorbent polymer 423 can be fully exhibited.
According to a preferred embodiment of the present invention, the adhesive 425 has elasticity, which makes it easier to balance the forces of the elongation of the adhesive present at the direct bonded portion caused by the swelling of the absorbent polymer 423 and the accompanying contraction of the adhesive, and efficiently exerts a bonding force that can support the absorbent polymer 423 at an appropriate position while ensuring a space in which the absorbent polymer 423 can swell. As a result, the liquid absorbency of the absorbent sheet 42 is further improved.

In order to make the above-mentioned effects more pronounced, the adhesive 425 preferably has a storage modulus G' of 10,000 Pa or more, more preferably 50,000 Pa or more at 25°C. The loss modulus G" of the adhesive 425 at 25°C is preferably 10,000 Pa or more, more preferably 50,000 Pa or more. By having the adhesive 425 have such values, the clamping force can be more efficiently exerted, which can simultaneously support the absorbent polymer at an appropriate position and ensure a space in which the absorbent polymer can swell. The storage modulus G' and the loss modulus G" can be measured, for example, by a method similar to the above-mentioned viscoelasticity measurement method. The storage modulus G' and the loss modulus G" can be adjusted by appropriately changing the composition and molecular weight of the base polymer contained in the adhesive 425, and the content of the plasticizer, etc.

It is preferable that the adhesive 425 is present on the surface of each fiber sheet 421, 422 facing the absorbent polymer 423 and in the gaps between the fibers that make up each fiber sheet 421, 422. This configuration makes it difficult for peeling to occur at the interface between each fiber sheet 421, 422 and the adhesive 425, and as a result, the absorbent polymer 423 can be held for a long time by the elastic force of the adhesive 425 present in the direct bonding portion 427. In order to confirm that the adhesive 425 is present in the gaps between the fibers that make up each fiber sheet 421, 422, the fiber sheet to be measured is cut to a predetermined size and the cross section is observed at a magnification of 50 to 500 times using a scanning electron microscope (for example, a scanning electron microscope "JCM-6000" manufactured by JEOL Ltd.).

It is preferable that the adhesive 425 is applied to each of the surfaces of the fiber sheet 421 facing the absorbent polymer 423 and the surface of the fiber sheet 422 facing the absorbent polymer 423. With this configuration, the adhesives applied to the fiber sheets 421 and 422 are bonded to each other to efficiently form the direct bonding portion 427 on the absorbent sheet 42, and it is possible to simultaneously support the absorbent polymer 423 at an appropriate position and secure a space in which the absorbent polymer 423 can swell. In addition, since the adhesive 425 can be easily present in the gaps between the fibers constituting the fiber sheets 421 and 422, there is also the advantage that peeling at the interface between the fiber sheets 421 and 422 and the adhesive 425 is less likely to occur.

As shown in Figs. 6(a) and (b), it is preferable that the application area of the adhesive 425 on the fiber sheet 422 is larger than that of the fiber sheet 421. With this configuration, the absorbent polymer 423 is uniformly held on the fiber sheet 422, which has a larger application area of the adhesive 425 than the fiber sheet 421, and the absorbent polymer 423 is prevented from unintentionally moving or falling off, and the liquid permeability from the fiber sheet 421, which has a smaller application area of the adhesive 425 than the fiber sheet 422, is ensured, and the liquid absorption speed can be increased. The application areas of both fiber sheets 421, 422 are compared by stacking the fiber sheets 421, 422 having the same shape and area so that there are no non-overlapping portions of the sheets. The application area of the adhesive 425 can be calculated, for example, by visualizing the presence of the adhesive 425 on the surface of the fiber sheets 421, 422 on which the adhesive 425 is attached using ink toner or the like, and calculating the area of the portion using image processing software or the like. If it is difficult to distinguish between them, the two sheets may be peeled off using a cold spray or the like before measurement.

In order to suppress unintended movement or falling off of the absorbent polymer 423 and to further increase the liquid absorption rate, it is preferable that the adhesive 425 is applied discontinuously to the bonding area of the fiber sheet 421 with the fiber sheet 422 so as to have non-applied areas, and that the adhesive 425 is applied continuously without gaps over the entire bonding area of the fiber sheet 422 with the fiber sheet 421. It is also preferable to use the surface of the fiber sheet 421 where the adhesive 425 is not present, i.e., the outer surface of the absorbent sheet 42 on the fiber sheet 421 side, as the liquid-receiving surface that is the surface where the absorbent sheet 42 and the liquid first come into contact. The bonding area is an area where the absorbent polymer 423 is arranged in a manner that does not allow gaps that can be macroscopically seen to be observed.

Examples of shapes in which the adhesive 425 is applied discontinuously to the fiber sheet 421 so as to have non-applied areas include a spiral shape, a summit shape, an omega shape, a curtain shape, a stripe shape, etc.

Regarding the positional relationship between the absorbent polymer 423 and the adhesive 425 in the thickness direction Z of the absorbent sheet 42, the area where the absorbent polymer 423 exists and the area where the adhesive 425 exists are the same. In detail, at least one of the following is included: (a) the area where the absorbent polymer 423 exists and the area where the adhesive 425 applied to the fiber sheet 421 exists are the same, but the area where the adhesive 425 applied to the fiber sheet 422 exists are not the same; (b) the area where the absorbent polymer 423 exists and the area where the adhesive 425 applied to the fiber sheet 422 exists are the same, but the area where the adhesive 425 applied to the fiber sheet 421 exists are not the same; and (c) the area where the absorbent polymer 423 exists and the area where the adhesive 425 applied to one fiber sheet exists are the same, and this area overlaps with the area where the adhesive applied to the other fiber sheet exists. In this embodiment, the area where the absorbent polymer 423 exists and the area where the adhesive 425 exists in the fiber sheet 422 are the same. Furthermore, the adhesive 425 on the fiber sheet 421 is applied discontinuously so as to have non-applied areas, and therefore there are portions where the non-applied areas and the areas of the fiber sheet 421 where the adhesive 425 is applied overlap.

Focusing on the portions of each of the fiber sheets 421 and 422 where the adhesive 425 is applied, it is preferable that the first basis weight of the adhesive 425 applied to the fiber sheet 421 is higher than the second basis weight of the adhesive 425 applied to the fiber sheet 422. This configuration makes it easier to form a direct bond portion 427 with the fiber sheet 422 via the adhesive 425 applied to the fiber sheet 421, and also makes it possible to hold the absorbent polymer 423 in an appropriate position via the adhesive 425 applied to the fiber sheet 422, thereby further improving the liquid absorption performance.

In addition, the sum of the first and second basis weights is preferably 500 g/m ² or less, more preferably 300 g/m ² or less, and even more preferably 200 g/m ² or less. The sum of the first and second basis weights is preferably 10 g/m ² or more, more preferably 50 g/m ² or more, and even more preferably 80 g/m ² or more. By adopting such a configuration, the retention of the absorbent polymer 423 between the fiber sheets is improved, and the swelling of the absorbent polymer 423 is not easily inhibited, so that the liquid absorption performance can be further improved.

From the same viewpoint, the first basis weight is preferably 400 g/m2 or ^less , more preferably 250 g/m2 or ^less , even more preferably 100 g/m2 or less, and more realistically 20 g/ ^m2 or more. The second basis weight is preferably 30 g/ ^{m2 or} less, more preferably 15 g/m2 ^or less, even more preferably 10 g/ ^m2 or less, and more realistically 2 g/m2 or ^more .

The first and second basis weights are measured and calculated only for the application portions of the fibrous sheets 421 and 422 where the adhesive 425 is applied. In detail, after separating the fibrous sheets 421 and 422 from each other in the absorbent sheet 42, the mass A1 (g) of the fibrous sheet 421 to which the adhesive 425 is attached is measured. In addition, the portion where the adhesive 425 is present is visualized on the surface of the fibrous sheet 421 to which the adhesive 425 is attached using ink toner or the like, and in this state, the total area S (m ² ) of the portion where the adhesive 425 is present is measured using image processing software. Next, the fibrous sheet 421 is immersed in an organic solvent to measure the mass A2 (g) of the fibrous sheet after dissolving the attached adhesive 425. The first basis weight (g/m ² ) can be calculated as "(A1-A2)/S". Similarly, the second basis weight (g/m ² ) can be calculated for the fibrous sheet 422 in the same manner as described above.

It is also preferable that the thickness of the adhesive 425 present on the surface of the fiber sheet 421 is greater than the thickness of the adhesive 425 present on the surface of the fiber sheet 422. This configuration makes it easier to form a direct bonded portion 427 with the fiber sheet 422 via the adhesive 425 applied to the fiber sheet 421, and also makes it possible to hold the absorbent polymer 423 in an appropriate position via the adhesive 425 applied to the fiber sheet 422, thereby further improving the liquid absorption performance.

From the same viewpoint, the thickness of the adhesive 425 present on the surface of the fiber sheet 421 is preferably 20 μm or more, more preferably 40 μm or more, and preferably 500 μm or less, more preferably 300 μm or less, provided that the thickness is thicker than the thickness of the adhesive 425 present on the surface of the fiber sheet 422. The thickness of the adhesive 425 present on the surface of the fiber sheet 422 is preferably 1 μm or more, more preferably 3 μm or more, and preferably 20 μm or less, more preferably 10 μm or less. The thickness of the adhesive 425 present on the surfaces of each fiber sheet 421, 422 is measured by cutting the fiber sheet to be measured to a predetermined size, observing the cross section at a magnification of 50 to 500 times using a scanning electron microscope (for example, a scanning electron microscope "JCM-6000" manufactured by JEOL Ltd.), measuring the thickness of the adhesive 425 protruding from the interface of the fiber sheet to be measured at five points, and the arithmetic average value is the thickness of the adhesive 425 (mm).

The absorbent sheet 42 has a peel strength between the two fiber sheets 421, 422 in a dry state of preferably 0.1 N/cm or more, more preferably 0.2 N/cm or more, even more preferably 0.3 N/cm or more, and preferably 3 N/cm or less, more preferably 2 N/cm or less, even more preferably 1.5 N/cm or less. By having such a peel strength, the absorbent sheet 42 can exhibit sufficient strength when in use, and the strength is maintained even after the absorbent sheet absorbs liquid. The dry state means that the moisture content of the absorbent sheet 42 is 20 mass% or less, calculated by the following formula from the weight change before and after heating overnight in a 105°C environment.
Moisture content % = (mass before drying - mass after drying) / mass before drying x 100

The peel strength can be measured, for example, by the following method. A test piece is prepared by cutting out a dry absorbent sheet. The shape of the test piece is a rectangle with a length in the longitudinal direction X of the absorbent sheet exceeding 80 mm and a length in the width direction Y of 25 mm. At one end of the longitudinal direction X of this test piece, the fiber sheet 421 and the fiber sheet 422 are peeled off, and the peeled parts are set in a T-shape in each chuck of a tensile tester. For example, an Autograph AG-X manufactured by Shimadzu Corporation is used as the tensile tester. The distance between the chucks is 20 mm. Peeling is performed at a tensile speed of 300 mm/min, and the test force average strength is measured. The measurement is performed three times, and the arithmetic average value of the test force average strength is taken as the peel strength (unit: N/25 mm).

The change in thickness of the absorbent sheet 42 when immersed in physiological saline for 30 minutes is preferably 2 mm or more, more preferably 3 mm or more, and even more preferably 4 mm or more, and realistically 20 mm or less. It is preferable that the change in thickness of the absorbent sheet 42 when immersed in physiological saline for 30 minutes increases within the above-mentioned range.
Furthermore, when the two fiber sheets 421, 422 are peeled away from each other after immersion in physiological saline for ³⁰ minutes, the number of locations where the two fiber sheets 421, 422 are directly bonded by the adhesive 425 is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more per 1 cm2. With this configuration, it is possible to improve both the swelling property and fixation property of the absorbent polymer, and the liquid absorbency is further increased.

The absorbent sheet 42 has a compressive deformation rate in a wet state of preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more, and 70% or less is practical. With such a configuration, the absorbent sheet 42 can maintain its flexibility even after the absorbent polymer swells due to liquid absorption, so that the absorbent sheet 42 feels good to the touch after absorbing liquid. The wet state refers to the state after the absorbent sheet 42 in a dry state is immersed in physiological saline in an amount 200 times the weight of the absorbent sheet 42 for 30 minutes, then left on a net and excess water is wiped off with paper.

The compression deformation rate can be measured, for example, using a KES-G5 handy compression tester manufactured by Kato Tech Co., Ltd. Specifically, an absorbent sheet having dimensions of 5 cm x 5 cm is immersed in physiological saline in an amount 200 times the weight of the absorbent sheet 42 for 30 minutes, and then attached to a test stand. Next, the absorbent sheet after immersion is compressed between steel plates having a circular flat surface with an area of 2 cm ^2. The compression speed is 20 μm/sec, and the maximum compression load is 490 mN/cm ² (=50 gf/cm ² ). When the thickness at a load of 4.9 mN/cm ² (0.5 gf/cm ² ) is thickness T0 (mm) and the thickness at a load of 490 mN/cm ² (50 gf/cm ² ) is thickness Tm (mm), the compression deformation rate (%) can be calculated as "100 x (T0 - Tm) / T0".

It is preferable that the absorbent sheet 42 has an uneven structure on the surface on which the adhesive 425 is not present on at least one of the fiber sheets 421 and 422. In particular, it is more preferable that the surface on which the adhesive 425 is not present on the fiber sheet 421 has an uneven structure, and that the surface on which the adhesive 425 is not present on the fiber sheet 422 does not have an uneven structure. By having such a configuration, it is possible to increase the surface area of the fiber sheet and increase the contact area with the liquid. In addition, when the absorbent sheet 42 is used with other members, friction is easily generated, and slippage can be reduced.

Examples of the uneven structure include a structure in which convex and concave portions are formed in a regular or irregular scattered pattern, and a shape having alternating ridges and grooves. Whether or not a structure is uneven is determined by, for example, whether the SMD measured by the method described below is 5 μm or more, which is considered to have an uneven structure, and whether or not the structure is uneven, which is considered to have no uneven structure, which is less than 5 μm.

[Method of measuring the mean deviation of surface roughness (SMD)]
The mean deviation of surface roughness SMD is measured by the following method using KESFB4-AUTO-A (product name) manufactured by Kato Tech Co., Ltd., in accordance with the method described in the following book.
"Standardization and Analysis of Texture Evaluation" by Toshio Kawabata, 2nd Edition, Texture Measurement and Standardization Research Committee, Japan Textile Machinery Association, July 10, 1980.

In detail, the absorbent sheet 42 is used as is, or the sheet 42 is cut out to prepare a test piece of 10 cm x 10 cm. This test piece is attached to a smooth metal test table. Next, a piano wire with a diameter of 0.5 mm is bent into a U-shape with a width of 5 mm and used as a contact, and the contact is pressed against the test piece at the contact surface with 9.8 cN (within ±0.49 cN tolerance). In this state, the test piece is moved horizontally for 2 cm at a constant speed of 0.1 cm/sec. A uniaxial tension of 19.6 cN/cm is applied to the test piece. The contact is pressed against a spring, the spring constant is 24.5 cN/mm (within ±0.98 cN/mm tolerance), and the resonant frequency is 30 Hz or more when it is away from the surface contact.

The measured value of the average deviation of the surface roughness is expressed as the SMD value. This measurement is performed in the direction along one side of the test piece (MD direction) and in the direction perpendicular to the MD direction (CD direction), and the SMD value in the MD direction (SMD _MD ) and the SMD value in the CD direction (SMD _CD ) are obtained, respectively. From the obtained SMD _MD and SMD _CD , the average deviation of the surface roughness SMD (μm) is calculated from the following formula (1). If a test piece of 10 cm x 10 cm cannot be prepared, the calculation is performed using the SMD value in either the MD direction or the CD direction.
Mean deviation of surface roughness SMD (μm)={(SMD _MD ² +SMD _CD ² )/2} ^1/2 (1)

Regarding the absorbent polymer 423 contained in the absorbent sheet 42, the basis weight of the absorbent polymer 423 is preferably 60 g/m ² or more, more preferably 80 g/m ² or more, even more preferably 100 g/m ² or more, and is preferably 700 g/m ² or less, more preferably 500 g/m ² or less, and even more preferably 400 g/m ² or less. By setting the basis weight of the absorbent polymer 423 within such a range, it is possible to efficiently manufacture an absorbent sheet 42 that achieves both the liquid absorbency of the absorbent polymer 423 and the retention of the absorbent polymer 423 by the direct bonded portion 427.

From the same viewpoint, the median particle size of the absorbent polymer 423 is preferably 800 μm or less, more preferably 650 μm or less, and even more preferably 500 μm or less. From the viewpoint of improving handling during the manufacture of the absorbent sheet, it is preferably 10 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. The median particle size of the absorbent polymer 423 can be obtained by graphing the particle size distribution obtained using a laser diffraction/scattering type particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.) as a cumulative distribution and determining it as the particle size corresponding to a cumulative ratio of 50%. The measurement conditions are as follows: 0.1% by mass of the absorbent polymer 423 is added to a dispersion medium containing 90% by mass of ethanol and 10% by mass of distilled water, and the mixture is stirred and dispersed for 3 minutes using built-in ultrasonic waves. The dispersed polymer dispersion is measured by the flow method using the above-mentioned measuring device to obtain the median particle size.

The absorbent polymer 423 contained in the absorbent sheet 42 has a swelling ratio of preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. In addition, the peel strength between the two fiber sheets 421, 422 in a wet state is preferably 0.1 N/25 mm or more, more preferably 0.2 N/25 mm or more, and even more preferably 0.3 N/25 mm or more, and is preferably 2.0 N/25 mm or less, more preferably 1.5 N/25 mm or less, and even more preferably 1.0 N/25 mm or less. By providing such a swelling ratio and peel strength, the liquid absorbency of the absorbent polymer 423 and the sheet strength after liquid absorption are further improved.
In this embodiment, 80% or more of the forming material of the absorbent sheet 42 is an absorbent polymer. The forming material of the absorbent sheet 42 here refers to an absorbent material that does not include the two fibrous sheets 421, 422. In other words, 80% by mass or more of the forming material of the absorbent sheet 42, excluding the fibrous sheets 421, 422, is an absorbent polymer.
In other words, the water-absorbent polymer occupancy rate in the absorbent sheet 42 is at least 80% by mass or more, preferably 85% by mass or more, and more preferably 90% by mass or more.

The swelling rate of the absorbent polymer was measured by cutting a nylon woven fabric (sold by Sanriki Seisakusho, product name: nylon net, specification: 250 mesh) into a rectangle 15 cm wide and 40 cm long, folding it in half at the center in the longitudinal direction, and heat sealing both ends to prepare a nylon bag 15 cm wide (inner dimension 14 cm) and 20 cm long. Next, two dry absorbent sheets 42 were prepared and cut into test pieces measuring 10 cm x 10 cm at the same location. One of the test pieces was placed in a nylon bag prepared without folding it, and immersed in physiological saline solution 200 times the mass of the test piece for 60 minutes. The test piece was then centrifuged at 143 x g for 10 minutes to dehydrate it. The mass X1 (g) of the test piece contained in the nylon bag was measured. Next, the other test piece (in a dry state) is separated into a fiber sheet, a fiber sheet, and an absorbent polymer using a cold spray or the like, and then similarly placed in a nylon bag and immersed in physiological saline in an amount 200 times the mass of the test piece for 30 minutes, and then the test piece is centrifuged at 143×g for 10 minutes to dehydrate. The mass X2 (g) of the test piece contained in the nylon bag at this time is measured. The swelling ratio (%) is calculated by "{(X1-Y1)/(X2-Y2)}×100". Y1 and Y2 in the above formula respectively represent the mass (g) of the nylon bag used when measuring the masses X1 and X2 after centrifugal dehydration. The peel strength between both fiber sheets 421 and 422 in a wet state can be measured in the same manner as the peel strength in a dry state after the absorbent sheet to be measured is impregnated with physiological saline under the above-mentioned conditions to make it wet, and then.

With regard to the distribution of the amount of absorbent polymer 423 present in absorbent sheet 42, it is preferable that absorbent polymer 423 is present uniformly in the sheet surface direction from the viewpoint of reducing the formation of unintended unevenness in the entire absorbent sheet 42 after swelling of absorbent polymer 423. "Present uniformly" means that the change in basis weight of absorbent polymer 423 measured at any part of the absorbent sheet is 0.5 or less as a coefficient of variation expressed by the formula standard deviation/arithmetic mean value.

On the other hand, from the viewpoint of further enhancing the liquid absorption performance in the central region of the sheet and preventing the absorbent polymer from falling off from the sheet ends while maintaining the liquid absorption and absorbent polymer retention, it is preferable that the amount of absorbent polymer present in the central region of the absorbent sheet 42 is greater than the amount of absorbent polymer 423 present at both ends of the absorbent sheet 42 in one direction, and it is even more preferable that the amount of absorbent polymer present in the central region of the absorbent sheet 42 is greater than the amount of absorbent polymer 423 present in the peripheral regions of the absorbent sheet 42.

When the amount of absorbent polymer in the central region of the absorbent sheet 42 is greater than the amount of absorbent polymer 423 at both ends or the periphery of the absorbent sheet 42, it is preferable that the number of direct bonded portions 427 at both ends or the periphery of the absorbent sheet 42 is greater than the number of direct bonded portions 427 in the central region of the absorbent sheet 42. In this case, it is also preferable that the adhesive application pattern in the central region of the absorbent sheet 42 and the adhesive application pattern at both ends or the periphery of the absorbent sheet 42 are the same. This configuration provides the ease of processing by applying the adhesive in the same pattern through the absorbent sheet 42, and the effect of preventing the absorbent polymer from spilling out from the ends by improving the adhesive strength in the peripheral portion.

The shape of the absorbent polymer 423 used in this embodiment is not particularly limited, and may be, for example, spherical, tufted, clumped, bale-shaped, fibrous, irregular, or a combination of these particles. From the viewpoint of increasing the uniformity of the dispersion of the absorbent polymer 423 during the manufacture of the absorbent sheet 42 and easily forming the absorbent sheet 42 having the direct bonding portion 427, it is preferable to use particles of the same shape for the absorbent polymer 423, and it is even more preferable that the coefficient of variation in the particle size distribution of the absorbent polymer 423 particles is 0.5 or less.

The coefficient of variation in particle size distribution can be measured, for example, by the following method. That is, using a laser diffraction/scattering particle size distribution measuring device (LA-920, manufactured by Horiba, Ltd.), absorbent polymer 423 is added to a dispersion medium of 90% by mass of ethanol and 10% by mass of distilled water so that the amount is 0.1% by mass, and the mixture is dispersed for 3 minutes by stirring and using built-in ultrasonic waves. The dispersed polymer dispersion is measured by the flow method using the measuring device described above to obtain the arithmetic mean value of particle size and the standard deviation of particle size. The value calculated by dividing the standard deviation by the arithmetic mean value is taken as the coefficient of variation.

Generally, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can be used as the absorbent polymer 423. Examples include polyacrylic acid and its salts, and polymethacrylic acid and its salts, specifically, partial sodium salts of acrylic acid polymers such as AQUALIC CA and AQUALIC CAW (both manufactured by Nippon Shokubai Co., Ltd.).

When the rate of change in bending rigidity per amount of thickness change before and after liquid absorption is defined as BR, calculated by the following formula, the BR of the absorbent sheet 42 in two directions arbitrarily selected from two mutually perpendicular directions and another direction intersecting the two directions without being perpendicular thereto is preferably 5.0/mm or less, more preferably 4.8/mm or less, and even more preferably 4.5/mm or less. There is no particular lower limit to the value of BR, but from the viewpoint of maintaining the shape of the absorbent body 4, it is preferably 0.1/mm or more, more preferably 0.3/mm or more.
BR=(B _w /B _d )/T0 _c
Bw : Bending rigidity of absorbent sheet 42 after absorbing liquid _Bd : Bending rigidity of absorbent sheet 42 before absorbing liquid _T0c : Amount of change in thickness of absorbent sheet 42 before and after absorbing liquid

(Method of measuring bending rigidity)
For the measurement, a handle-ometer tester manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd., which conforms to the bending resistance measurement method specified in JIS L1096 (general woven fabric test method), was used. A square shape in plan view of 100 mm in the direction of the object to be measured and 100 mm in the direction perpendicular to the direction of the object to be measured was cut out from the object to be measured (absorbent sheet 42), and two of the cut-out pieces were stacked to form a test piece. The slot distance in the sample stand provided in the tester was adjusted to 10 mm, the test piece was placed so as to span the slots, and the four corners of the test piece were fixed to the upper surface of the sample stand with adhesive tape. At this time, the test piece was placed so that the direction of the test piece to be measured coincided with the direction between the slots, the center of the direction of the test piece to be measured was located in the center between the slots, and the test piece was horizontal. The blade, adjusted to descend to a position (lowest position) 7 mm below the upper surface of the sample table, was lowered from above the test piece at a constant speed of 200 mm/min, and the maximum value (cN) indicated by the indicator (load meter) when the blade pressed the test piece was read. Such measurements were performed five times, and the average value was calculated to determine the bending stiffness value of the test piece. The measurements were performed at room temperature of 23±2°C and relative humidity of 50% RH±5%.

As described above, the bending stiffness _Bw is the bending stiffness in one direction of the absorbent sheet 42 after absorbing liquid, so the test piece used in the above measurement method is the "test piece after absorbing liquid". This test piece after absorbing liquid is prepared by the following procedure. A dry test piece is immersed in physiological saline for 30 minutes, and then the moisture is wiped off using an absorbent sheet such as Kimtowel to the extent that no moisture leaks from the test piece (test piece after absorbing liquid). This is used as the test piece.

When the member to be measured is bonded to another member with an adhesive, such as the absorbent sheet 42 in the absorbent body 4, the adhesive force is removed from the bonded portion by, for example, spraying cold air from a cold spray to an extent that does not affect the contact angle of the fibers, before the sample is removed. This procedure is common to all measurements in this specification.

The rate of change in bending rigidity BR per thickness change before and after liquid absorption is an index of the distribution state of the absorbent polymer 423 in the absorbent sheet 42. In other words, it is a matter related to the distribution of the absorbent polymer 423. The rate of change in bending rigidity BR being 5.0/mm or less means that the change in bending rigidity in a predetermined direction before and after liquid absorption for the absorbent sheet 42, particularly that for the absorbent sheet 42 which is the dominant factor of the bending rigidity _Bd and _Bw, is small, and this is an index of the absorbent polymer 423 being uniformly distributed in the absorbent sheet 42. When the rate of change in bending rigidity BR is within the specific range, that is, when the absorbent polymer 423 is uniformly distributed in the absorbent sheet 42, the liquid absorption performance of the absorbent sheet 42 is improved, and the increase in thickness of the absorbent sheet 42 due to liquid absorption is suppressed, and the absorbent sheet 42 can exhibit excellent flexibility and liquid absorption performance even after liquid absorption. The BR in two directions arbitrarily selected from three directions, namely, two directions perpendicular to each other and another direction intersecting the two directions without being perpendicular to them, is preferably 0.1/mm or more, more preferably 0.3/mm or more, and is preferably 4.8/mm or less, more preferably 4.5/mm or less.

From the viewpoint of ensuring the effect of the uniform distribution of the absorbent polymer 423 in the absorbent sheet 42, it is preferable that not only the bending stiffness change rate BR in one direction but also the bending stiffness change rates BR in multiple directions are within a specific range for a specific region in the absorbent sheet 42, for example, the region located in the crotch portion C. More specifically, it is preferable that the bending stiffness change rate BR in any two directions selected from any three directions of the absorbent sheet 42, for example, the vertical direction X, the horizontal direction (width direction Y), and the diagonal direction D, are each within a specific range. The most preferable form is a form in which the bending stiffness change rate BR in any three directions for any region in the absorbent sheet 42 is each within the above-mentioned specific range. The diagonal direction D is any direction other than the vertical direction X and the horizontal direction (width direction Y), and generally refers to a direction at 45 degrees to the vertical direction X (and therefore 45 degrees to the horizontal direction Y).

The bending rigidity of the absorbent sheet 42 before absorbing liquid in one direction, specifically, for example, the longitudinal direction X, the transverse direction (width direction Y) or the diagonal direction D, is preferably 0.1 mN·cm ² /cm or more, more preferably 0.2 mN·cm ² /cm or more, and preferably 19.6 mN·cm ² /cm or less, more preferably 15.0 mN·cm ² /cm or less.

The present invention has been described above based on its preferred embodiment, but the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the spirit of the present invention as described in the claims, unless otherwise limited in the above description.

In relation to the above-mentioned embodiment, the present invention further discloses the following absorbent article.
＜1＞
The device comprises a top sheet, a back sheet, and an absorbent body disposed between these sheets;
the top sheet covers the skin-facing surface of the absorbent body, and has a pair of extending portions extending laterally from each side edge of the absorbent body, each of the extending portions being folded back at each side edge of the absorbent body to cover each side of the non-skin-facing surface of the absorbent body,
Each of the extensions is joined to a non-skin side member adjacent to the absorbent body on a non-skin facing surface thereof,
The absorbent body has an absorbent sheet including two identical or different fibrous sheets and absorbent polymer particles disposed between the fibrous sheets;
Elastic members are disposed along each side edge of the absorbent body between the absorbent body and the top sheet,
When the elastic members contract, each side of the absorbent body can stand up from a joining position between the absorbent body and the non-skin side member as a starting point,
An absorbent article, wherein the absorbent sheet is present at least in a portion of the absorber that can stand up due to contraction of each of the elastic members.

＜2＞
The absorbent article according to <1>, wherein 80% by mass or more of the material forming the absorbent sheet, excluding the fiber sheet, is an absorbent polymer.
＜3＞
The absorbent article according to <1> or <2>, wherein the absorbent body further has an auxiliary layer having a structure different from that of the absorbent sheet.
＜4＞
The absorbent article according to <3>, wherein the auxiliary layer is disposed between the riseable portions of the absorbent body.
＜5＞
The absorbent article according to <4>, wherein the absorbent body has a stiffness value in a central region in a width direction of the absorbent article that is more than twice the stiffness value of the absorbent sheet alone.

＜6＞
The absorbent article according to any one of <3> to <5>, wherein the auxiliary layer is made of a mixed laminate of fluff pulp and absorbent polymer particles.
＜７＞
The absorbent article according to <6> above, wherein the basis weight of the absorbent polymer in the auxiliary layer is preferably 65 to 800 g/m ² , more preferably 70 to 600 g/m ² .
＜8＞
The absorbent article according to <6> or <7>, wherein the basis weight of the fluff pulp in the auxiliary layer is preferably 80 to 600 g/m ² , more preferably 100 to 400 g/m ² .
＜9＞
The absorbent article described in any one of <6> to <8>, wherein PR1 is the ratio of the absorbent polymer content by mass of the auxiliary layer to the total mass of the constituent materials of the auxiliary layer, and PR2 is the ratio of the absorbent polymer content by mass of the absorbent sheet to the total mass of the constituent materials of the absorbent sheet. The ratio PR2/PR1 of PR2 to PR1 is preferably 1.1 or more, more preferably 1.3 or more, preferably 5.0 or less, more preferably 3.5 or less, preferably 1.1 or more and 5.0 or less, and more preferably 1.3 or more and 5.0 or less.
＜10＞
When the mass ratio of the absorbent polymer to the material constituting the absorbent body (excluding fiber materials other than the fiber material constituting the auxiliary layer and adhesive) is defined as FSR,
The absorbent article according to any one of <6> to <9>, wherein the FSR in the standable portion of the absorber is greater than the FSR in a portion between the standable portions.

<11>
The auxiliary layer has a low stiffness portion extending in the longitudinal direction of the absorbent article,
The absorbent article according to any one of <3> to <10>, wherein the low stiffness portion is located between the riseable portions of the absorber.
＜12＞
The absorbent article according to any one of <3> to <11>, wherein a thickness change amount of the auxiliary layer before and after absorbing liquid is larger than that of the absorbent sheet.
＜13＞
The absorbent article described in <12> above, wherein the change in thickness of the absorbent sheet before and after liquid absorption is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 25 mm or less, more preferably 15 mm or less, and also preferably 0.5 mm or more and 25 mm or less, more preferably 1 mm or more and 15 mm or less.
＜14＞
The absorbent article described in <12> or <13>, wherein the change in thickness of the auxiliary layer before and after liquid absorption is preferably 2 mm or more, more preferably 4 mm or more, and preferably 45 mm or less, more preferably 35 mm or less, and also preferably 2 mm or more and 45 mm or less, more preferably 4 mm or more and 35 mm or less.

＜15＞
The absorbent article described in any one of <12> to <14>, wherein the difference when the thickness change in the auxiliary layer is subtracted from the thickness change in the absorbent sheet is preferably 1 mm or more, more preferably 2 mm or more, preferably 20 mm or less, more preferably 15 mm or less, and preferably 1 mm or more and 20 mm or less, more preferably 2 mm or more and 15 mm or less.
＜16＞
The auxiliary layer has a recess that serves as a low-rigidity portion extending in the longitudinal direction of the absorbent article,
The absorbent article according to any one of <12> to <15>, wherein the recess is formed in the auxiliary layer so as to be located between standable portions of the absorbent body.
＜１７＞
The absorbent sheet has two fibrous sheets that are not joined to each other at both side edges and in the vicinity thereof,
The absorbent article according to any one of <1> to <16>, wherein the elastic member is disposed in the non-joined portion.
＜18＞
The absorbent article according to any one of <1> to <17>, wherein the absorbent sheet is located in an area of at least 75% of the length of the standable portion of the absorbent body inwardly from the side edge of the absorbent body.

＜19＞
The absorbent article according to <18> above, wherein the proportion of the absorbent sheet is preferably 78% or more, more preferably 82% or more, and even more preferably 85% or more.
＜20＞
The absorbent sheet has both of the fiber sheets bonded together with an adhesive,
In the region where the absorbent polymer is disposed, the absorbent polymer is disposed in a manner such that no gaps that can be macroscopically recognized are observed,
The absorbent article according to any one of <1> to <19>, wherein in the region, both fiber sheets have a portion where they are directly bonded to each other by the adhesive without the absorbent polymer being interposed therebetween.
＜21＞
The absorbent article described in <20> above, having a portion where the two fibrous sheets are directly bonded by the adhesive without the absorbent polymer interposed therebetween, and a portion where the two fibrous sheets are bonded by the adhesive via the absorbent polymer.

＜22＞
The absorbent article according to <20> or <21>, wherein a relaxation time of the adhesive obtained by viscoelasticity measurement is 1 second or more at 50° C.
＜23＞
an application area of the adhesive on one of the fiber sheets is larger than an application area of the adhesive on the other of the fiber sheets;
The absorbent article according to any one of <20> to <22>, wherein in a region where the adhesive is applied, the basis weight of the adhesive in the other fiber sheet is higher than the basis weight of the adhesive in the one fiber sheet.
＜24＞
The absorbent article according to any one of <20> to <23>, wherein the adhesive has a storage modulus at 25° C. of preferably 10,000 Pa or more, more preferably 50,000 Pa or more.
＜25＞
The absorbent article according to any one of <20> to <24>, wherein the adhesive has a loss modulus at 25° C. of preferably 10,000 Pa or more, more preferably 50,000 Pa or more.
＜26＞
The absorbent article according to any one of <20> to <25>, wherein the adhesive is applied discontinuously to a bonding area of one of the fiber sheets with the other of the fiber sheets so as to have non-applied areas, and the adhesive is applied continuously without gaps to an entire bonding area of the other of the fiber sheets with the one of the fiber sheets.

＜27＞
The absorbent article according to any one of <20> to <26>, wherein the sum of a first basis weight of the adhesive applied to one of the fiber sheets and a second basis weight of the adhesive applied to the other of the fiber sheets is preferably 500 g/ ^m2 or less, more preferably 300 g/m2 or ^less , and even more preferably 200 g/m2 ^or less, and the sum of the first basis weight and the second basis weight is preferably 10 g/ ^m2 or more, more preferably 50 g/m2 or ^more , and even more preferably 80 g/m2 or ^more .
＜28＞
The absorbent article according to <27>, wherein the first basis weight is preferably 400 g/m2 or ^less , more preferably 250 g/m2 ^or less, even more preferably 100 g/m2 ^{or less} , and practically 20 g/m2 or ^more .
＜29＞
The second basis weight is preferably 30 g/m2 ^or less, more preferably 15 g/m2 ^or less, and even more preferably 10 g/m2 ^or less, and is practically 2 g/m2 or ^more . The absorbent article according to <27> or <28>.
＜30＞
The absorbent article according to any one of <20> to <29>, wherein the thickness of the adhesive present on one surface of the fiber sheet is greater than the thickness of the adhesive present on the other surface of the fiber sheet.
＜31＞
The absorbent article according to <30>, wherein the thickness of the adhesive present on one surface of the fiber sheet is preferably 20 μm or more, more preferably 40 μm or more, and is preferably 500 μm or less, more preferably 300 μm or less.

＜32＞
The absorbent article according to <30> or <31>, wherein the thickness of the adhesive present on the other surface of the fiber sheet is preferably 1 μm or more, more preferably 3 μm or more, and is preferably 20 μm or less, more preferably 10 μm or less.
＜33＞
The absorbent article according to any one of <20> to <32>, wherein, when the rate of change in bending rigidity per unit thickness change before and after liquid absorption of the absorbent sheet calculated by the following formula (1) is defined as BR, the BR in two directions arbitrarily selected from three directions, i.e., two mutually perpendicular directions and another direction intersecting the two directions without being perpendicular thereto, is 5.0/mm or less.
BR=(B _w /B _d )/T0 _c (1)
_Bw : bending rigidity of the absorbent sheet after absorbing liquid _Bd : bending rigidity of the absorbent sheet before absorbing liquid _T0c : change in thickness of the absorbent sheet before and after absorbing liquid, calculated by the following formula (2) _T0c = _T0w - _T0d (2)
_T0w : Thickness of the absorbent sheet under a load of 4.9 mN/ ^cm2 after absorbing liquid _T0d : Thickness of the absorbent sheet under a load of 4.9 mN/ ^cm2 before absorbing liquid <34>
The absorbent article according to the above item <33>, wherein the bending stiffness change rate BR is preferably 4.8/mm or less, and more preferably 4.5/mm or less.
＜35＞
The absorbent article according to the above <33> or <34>, wherein the bending stiffness change rate BR is preferably 0.1/mm or more, more preferably 0.3/mm or more.

＜36＞
The absorbent article according to any one of <33> to <35>, wherein the flexural rigidity of the absorbent sheet before liquid absorption in one direction, specifically, for example, the longitudinal direction X, the transverse direction (width direction Y) or the diagonal direction D, is preferably 0.1 mN·cm ² /cm or more, more preferably 0.2 mN·cm ² /cm or more, and preferably 19.6 mN·cm ² /cm or less, more preferably 15.0 mN·cm ² /cm or less.
＜３７＞
Leak-proof cuffs are formed on both sides of the absorbent body in the longitudinal direction,
The absorbent article according to any one of <1> to <36>, wherein the leakage preventing cuffs are provided with elastic members for pulling the leakage preventing cuffs together.
＜３８＞
The leak-proof cuff includes a leak-proof cuff-forming sheet,
The top sheet is joined and fixed to the back sheet and the leak-proof cuff forming sheet at both side edges thereof to form a main body joining and fixing portion which is a joining position;
The absorbent article includes an exterior body on a non-skin contact surface side of the absorbent body,
The exterior body and the sheet for forming the leak-proof cuffs are joined by an exterior body joining and fixing part,
The absorbent article according to <37>, wherein the exterior body joint fixing portion is disposed at a position outside the main body joint fixing portion in the absorbent article width direction.

＜３９＞
The absorbent article described in any one of <1> to <38>, wherein the stiffness value in the central region of the absorbent article is preferably 2.0 times or more, more preferably 3.0 times or more, and even more preferably 4.0 times or more of the stiffness value of the absorbent sheet alone.
＜40＞
The absorbent article described in any one of <1> to <39>, wherein the fiber sheets are formed in a non-bonded state at both side edges and the vicinity thereof of the absorbent sheet, and elastic members are respectively arranged in the non-bonded portions.
＜41＞
The absorbent article according to any one of <1> to <40>, wherein the absorbent sheet has a peel strength between both fiber sheets in a dry state of preferably 0.1 N/cm or more, more preferably 0.2 N/cm or more, even more preferably 0.3 N/cm or more, and preferably 3 N/cm or less, more preferably 2 N/cm or less, even more preferably 1.5 N/cm or less.
＜42＞
The absorbent article according to any one of <1> to <41>, wherein the absorbent polymer contained in the absorbent sheet has a swelling rate of preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more.

＜43＞
The absorbent article according to any one of <1> to <42>, wherein the peel strength between the two fiber sheets in a wet state is preferably 0.1 N/25 mm or more, more preferably 0.2 N/25 mm or more, even more preferably 0.3 N/25 mm or more, and is preferably 2.0 N/25 mm or less, more preferably 1.5 N/25 mm or less, even more preferably 1.0 N/25 mm or less.
＜44＞
The absorbent sheet has a thickness, measured under a pressure of 1.7 kPa, of preferably 0.3 mm or more, more preferably 0.6 mm or more, and preferably 4 mm or less, more preferably 3 mm or less, and even more preferably 2 mm or less. The absorbent article according to any one of <1> to <43>.

According to the present invention, an absorbent article is provided in which both sides of the absorbent body remain flexible even after absorbing liquid, thereby reducing the feeling of chafing caused by the wearer's movements while wearing the article.

Claims (13)

The device comprises a top sheet, a back sheet, and an absorbent body disposed between these sheets;
the top sheet covers the skin-facing surface of the absorbent body, and has a pair of extending portions extending laterally from each side edge of the absorbent body, each of the extending portions being folded back at each side edge of the absorbent body to cover each side of the non-skin-facing surface of the absorbent body,
Each of the extensions is joined to a non-skin side member adjacent to the absorbent body on a non-skin facing surface thereof,
the absorbent body has an absorbent sheet including a first fibrous sheet and a second fibrous sheet which are the same or different, and particles of an absorbent polymer disposed between the first fibrous sheet and the second fibrous sheet ;
The absorbent sheet has a thickness of 0.3 mm or more and 4 mm or less when measured under a pressure of 1.7 kPa,
The absorbent sheet has both of the fiber sheets bonded together with an adhesive,
In the region where the absorbent polymer is disposed, the absorbent polymer is disposed in a manner such that no gaps that can be macroscopically recognized are observed,
In the region, the two fibrous sheets have a direct bonding portion where they are bonded directly by the adhesive without the absorbent polymer therebetween, and a portion where the two fibrous sheets are bonded by the adhesive via the absorbent polymer;
When viewed in cross section in the thickness direction of the absorbent sheet, the direct bonding portion is such that the adhesive forms columns to directly bond the two fiber sheets together,
the adhesive is applied discontinuously to a bonding region of the first fiber sheet with the second fiber sheet so as to have non-applied portions, and the adhesive is applied continuously without gaps over the entire bonding region of the second fiber sheet with the first fiber sheet,
an outer surface of the absorbent sheet on the side of the first fiber sheet is used as a liquid-receiving surface;
Elastic members are disposed along each side edge of the absorbent body between the absorbent body and the top sheet,
When the elastic members contract, each side of the absorbent body can stand up from a joining position between the absorbent body and the non-skin side member as a starting point,
An absorbent article, wherein the absorbent sheet is present at least in a portion of the absorber that can stand up due to contraction of each of the elastic members. The absorbent article according to claim 1 , wherein 80% by mass or more of the material forming the absorbent sheet, excluding both of the fibrous sheets, is an absorbent polymer. The absorbent article according to claim 1 or 2 , wherein the absorbent body further comprises an auxiliary layer having a structure separate from the absorbent sheet. The absorbent article according to claim 3 , wherein the auxiliary layer is disposed between the riseable portions of the absorbent body. The absorbent article according to claim 4 , wherein the absorbent body has a stiffness value in a central region in the width direction of the absorbent article that is at least twice as high as a stiffness value of the absorbent sheet alone. The absorbent article according to claim 3 , wherein the auxiliary layer is made of a mixed laminate containing at least water-absorbent natural fibers and an absorbent polymer. When the mass ratio of the absorbent polymer to the total amount of the absorbent material other than the two fiber sheets in the absorbent sheet and the absorbent material in the auxiliary layer is defined as FSR,
The absorbent article according to claim 6 , wherein the FSR of the absorbent body at the standable portions is greater than the FSR of portions between the standable portions. The auxiliary layer has a low stiffness portion extending in the longitudinal direction of the absorbent article,
The absorbent article according to claim 3 , wherein the low stiffness portion is located between the riseable portions of the absorbent body. The absorbent article according to claim 3 , wherein a change in thickness of the auxiliary layer before and after liquid absorption is greater than that of the absorbent sheet. The absorbent article according to any one of claims 1 to 9 , wherein the absorbent sheet is positioned in the upstandable portion of the absorbent body over an area of at least 75% of the length of the absorbent body inwardly from the side edge of the absorbent body. 11. The absorbent article according to claim 1, wherein the relaxation time of the adhesive obtained by viscoelasticity measurement is 1 second or more at 50°C. an application area of the adhesive on the second fiber sheet is larger than an application area of the adhesive on the first fiber sheet;
12. The absorbent article according to claim 1 , wherein the basis weight of the adhesive in the first fibrous sheet is higher than the basis weight of the adhesive in the second fibrous sheet at the portion where the adhesive is applied. 13. The absorbent article according to claim 1, wherein, when the rate of change in bending rigidity of the absorbent sheet per unit thickness change before and after liquid absorption, calculated by the following formula (1), is defined as BR, the BR in two directions arbitrarily selected from three directions, i.e., two mutually perpendicular directions and another direction intersecting the two directions without being perpendicular thereto, is 5.0/mm or less.
BR=(B _w /B _d )/T0 _c (1)
_Bw : bending rigidity of the absorbent sheet after absorbing liquid _Bd : bending rigidity of the absorbent sheet before absorbing liquid _T0c : change in thickness of the absorbent sheet before and after absorbing liquid, calculated by the following formula (2) _T0c = _T0w - _T0d (2)
_T0w : Thickness of the absorbent sheet after absorbing liquid under a load of 4.9 mN/ ^cm2 _T0d : Thickness of the absorbent sheet before absorbing liquid under a load of 4.9 mN/ ^cm2

Images